chain tightening - 2018 KTM 790 Duke Forum
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post #1 of 16 (permalink) Old 04-15-2019, 01:25 PM Thread Starter
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chain tightening

Dear duke lovers,


I kinda fail at figuering out how best to measure when i need to tighten my chain..



How do you guys do it?


Thanks!
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post #2 of 16 (permalink) Old 04-16-2019, 07:20 AM
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So glad you asked ...

Because Iíve got no idea either!!

After 20 years on shaft driven bikes Iíve never adjusted a chain. My reading of the manual suggests that when pushing the lower run of the chain upwards in the middle it should *almost* (2-5mm) touch the swing arm. My chain touches easily so Iíve been preparing myself for an hour of skinned knuckles, swearing and rounded nuts.

Any tips from the forum would be appreciated...

Tom in Sydney
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post #3 of 16 (permalink) Old 04-16-2019, 07:41 AM
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it's a tricky one... as the debate is that the output shaft issues with leaky seals may be caused by chains being too tight.

If you do it on a paddock stand as per the manual, then sit on your bike you can see/feel just how tight it then becomes... So do we run it loose at measuring... I don't know.

Mine is slightly looser now than the manual suggests.
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post #4 of 16 (permalink) Old 04-16-2019, 09:17 PM
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I have had strangers tell me i need to tighten my chain

I believe the 790 has to be run a looser i assume because it has a longer swing arm?
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post #5 of 16 (permalink) Old 04-17-2019, 09:33 AM
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It really is pretty simple.

I put an auto jack with a small block of wood on top under the rhs foot rest, this will lift the bike and unload the rear shock so that the swing arm drops to full extension, the rear wheel only needs to be just high enough to turn. You should also put a strap around the front brake lever and the throttle so that the bike can't move forward.

I have measured on the swing arm where the adjustment point is and put a small dot of white paint on the swing arm.

Underneath the swing arm where the chain would hit I stick a piece of metal 4mm thick on the swing arm with double sided tape (this is temporary, I remove when finished)

It is just a simple matter to rotate the rear wheel and check that the chain just contacts the piece of 4mm thick metal, check about every 30cm of chain. The reason the tension is checked about every 30cm of chain is that the rear sprocket can be mounted slightly off centre which would give the effect of a tight spot in the chain - always adjust the chain in the tightest position.

Remove the piece of metal used for measuring, remove the strap around the front brake.
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post #6 of 16 (permalink) Old 04-17-2019, 07:40 PM
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Quote:
Originally Posted by wozzamatta View Post
It really is pretty simple.

I put an auto jack with a small block of wood on top under the rhs foot rest, this will lift the bike and unload the rear shock so that the swing arm drops to full extension, the rear wheel only needs to be just high enough to turn. You should also put a strap around the front brake lever and the throttle so that the bike can't move forward.

I have measured on the swing arm where the adjustment point is and put a small dot of white paint on the swing arm.

Underneath the swing arm where the chain would hit I stick a piece of metal 4mm thick on the swing arm with double sided tape (this is temporary, I remove when finished)

It is just a simple matter to rotate the rear wheel and check that the chain just contacts the piece of 4mm thick metal, check about every 30cm of chain. The reason the tension is checked about every 30cm of chain is that the rear sprocket can be mounted slightly off centre which would give the effect of a tight spot in the chain - always adjust the chain in the tightest position.

Remove the piece of metal used for measuring, remove the strap around the front brake.
The first sentence of your post contradicts the rest of it.
I have owned a lot of bikes and getting the correct chain tension has never been that complicated.
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post #7 of 16 (permalink) Old 04-17-2019, 09:07 PM
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My previous chain driven bikes were all dirt bikes. The way you adjusted the chain on them was to compress the suspension which would make the chain tighten. While compressed you wanted a very slight amount of play. As the swingarm goes back down the chain would loosen. Thought this would be the same...
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post #8 of 16 (permalink) Old 04-18-2019, 11:39 AM
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Quote:
Originally Posted by Rocky R View Post
My previous chain driven bikes were all dirt bikes. The way you adjusted the chain on them was to compress the suspension which would make the chain tighten. While compressed you wanted a very slight amount of play. As the swingarm goes back down the chain would loosen. Thought this would be the same...
this, leave just a bit of play when the bike is laden, it's quite slack when not compressed, although I'm a 'bigger' rider.

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post #9 of 16 (permalink) Old 04-24-2019, 03:04 PM

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Quote:
Originally Posted by Rocky R View Post
My previous chain driven bikes were all dirt bikes. The way you adjusted the chain on them was to compress the suspension which would make the chain tighten. While compressed you wanted a very slight amount of play. As the swingarm goes back down the chain would loosen. Thought this would be the same...
Agreed. As cumbersome as it sounds, I would do this on a stand and off a stand. Sometimes I need to loosen the bolt and adjust again if it was too tight. I tightened my chain once with a friend where I left the rear axle nut loose and pulled the wheel all the way back to make the chain tight. Then sat on the bike (full weight) and had my buddy run the set screws out to the block. Then I would back them in a bit, push the block/axle up against the screws and tighten the nut. Never really had a problem with tightening the chain. Did this on dirt and sport bikes.
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post #10 of 16 (permalink) Old 04-25-2019, 12:03 PM
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I had the same issue with my 790, people saying the chain was too slack and required tightening... Don't. To check tightness the manual advises checking the tension by keeping top of chain taught whilst using a finger to push bottom/middle part of the chain up to the chain sliding piece and then measure tension from there to the rear sprocket. Then when adjusted sit on the bike and check it's not tight again at the bottom otherwise the chain will be under even more tension when you ride of bumps etc. This KTM set up should look slack when on the side stand. I spoke with my local mechanic who says most of the time he slackens off chains rather than tightening them. Yes, you need 3 arms and a friend

Last edited by PitMoggy; 04-25-2019 at 12:04 PM. Reason: spelling
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